Simulation of impacts of cuboidal and spherical wet agglomerates of fine particles

In this contribution, a simulation tool is developed based on the discrete element method (DEM) and contact mechanics, which is able to investigate the deformation and attritionof wet agglomerates during different impact conditions. In the research, two types of agglomerates of particles are formed, namely, cuboidal and spherical agglomerates. The models of liquid and solid bridge have been implemented in the DEM to perform a detailed simulation for a better understanding of the soft, non-elastic deformation behavior of cuboidal and spherical wet agglomerates. As a result, the dependency of the restitution coefficient on the viscosity of the binder, impact velocity and agglomerate shape are obtained. Our research demonstrates that, unlike dry particle agglomerates, the attrition patterns of wet agglomerates cannot be classified as 'fracture'. Interestingly, it is observed for the first time that the number of liquid bridges inside a wet agglomerate, when impacted, experiences a significant drop before accumulating and exceeding the original number of liquid bridges. This phenomenon is discovered for the first time. For instance, when impacting a cuboidal agglomerate with liquid viscosity of 50mPa•s at a velocity of 2m/s, the number of liquid bridges drops from 9400 to ca. 8700, then increase up to ca. 11300; This research reveals that some wet agglomerates with lower liquid viscosity can rebound, while the coefficient of restitution tends to zero when liquid viscosity is increased.